You're using PC or Mac? I think there're other btr SC you can get with Rm400.

I see, what speaker r u using rite now? Frankly speaking, I've tried the Creative X-Fi but it wasn't really impressive. If you're got gd speaker, may be you can consider the Audiotrak product. Here I quoted some explanation from Akabane.

1.Sound Blaster X-Fi Surround 5.1 -Suitable for gaming (most of time is gaming the best), movie not bad
2.ASUS XONAR U1 - Very good in gaming even music got virtual surround which is real in headphone..movie yes . but still support 2.1 channel or 2.0 or headphone..
3.Maya 44 USB - Production sound card, well balance , not suitable for gaming, Music is the mainly use item..playback is very good like HD2
4. Maya EX5CE - Main thing is music, not for gaming-but if you insist just a little 3d sensura support. Movie is good. Can be use as 7.1 channel or headphone out, minor production can be use..

If you're only choosing btw X-Fi and Audigy, then just grabbed the X-Fi coz the audigy is kinda old ady, I'm afraid it's not fully supported.